The present invention relates to a new and improved process for flotation beneficiation of non-sulfide value minerals from ores containing them together with substantial quantities of associated siliceous gangue minerals and materials. More particularly, it relates to a new and improved process wherein a depressant compound is employed in non-sulfide flotations employing anionic collectors to provide improved grade and recovery of valuable non-sulfide minerals in a reduced number of flotation steps.
Froth flotation is one of the most widely used processes for beneficiating ores containing valuable minerals. It is especially useful for separating finely ground valuable minerals from their associated gangue or for separating valuable minerals from one another. The process is based on the affinity of suitably prepared mineral surfaces for air bubbles. In froth flotation, a froth or a foam is formed by introducing air into an agitated pulp of the finely ground ore in water containing a frothing or foaming agent. A chief advantage of separation by froth flotation is that it is a relatively efficient operation at a substantially lower cost than many other processes.
Current theory and practice state that the success of a froth flotation process depends to a great degree on reagents called collectors that impart selective hydrophobicity to the value mineral that has to be separated from other minerals. Thus, the flotation separation of one mineral species from another depends upon the relative wettability of mineral surfaces by water. Typically, the surface free energy is purportedly lowered by the adsorption of heteropolar collectors. The hydrophobic coating thus provided acts in this explanation as a bridge so that the mineral particles may be attached to an air bubble. The practice of this invention is not, however, limited by this or other theories of flotation.
In addition to the collectors, several other reagents may also be necessary for successful results. Among these, the frothing agents are used to provide a stable flotation froth, persistent enough to facilitate the mineral separation, but not so persistent that it cannot be broken down to allow subsequent processing.
Moreover, certain other important reagents such as the modifiers are also largely responsible for the success of flotation separation of minerals. Modifiers include all reagents whose principal function is neither collecting nor frothing but one of modifying the surface of the mineral so that a collector either adsorbs to it or does not. Modifying agents can thus be considered as depressants, activators, pH regulators, dispersants, deactivators, etc. Often, a modifier may perform several functions simultaneously.
The present invention is primarily directed to the flotation of non-sulfide minerals which present special problems by virtue of the great similarity between the surface properties of the value non-sulfide minerals and the surface properties of the non-sulfide gangue minerals. It is often the case that the differences between flotation characteristics of various non-sulfide minerals are not any greater than those between samples of a single mineral from different deposits. As can be appreciated, efficient and selective separation of one mineral from other non-sulfide value minerals and gangue minerals is a sensitive operation which depends upon a large number of variables.
Non-sulfide minerals respond to flotation with a large number of anionic collectors such as carboxylates, for example the fatty acids, and sulfonates and sulfonates. The fatty acids are used most commonly in commercial applications because of their low cost and effectiveness. Fatty acids are quite often non-selective, however, requiring a careful adjustment of flotation conditions, and it is generally necessary to use appropriate modifiers. The fatty acid collectors have a high surface activity which introduces non-selectivity to the system and in many flotation systems the problems of non-specific flotation remain largely unresolved.
In prior art non-sulfide flotation systems wherein fatty acids are used as the collectors, the use of modifying agents of an inorganic type such as sodium phosphates, sodium fluoride, hydrofluoric acid, sodium silicate, chromates and cichromates, as well as, organic modifiers such as starches, guars and tannins, has been essential to achieve selectivity in the systems. The mechanisms by which these reagents react, however, have remained secure, primarily because of the lack of systematic data in the literature on their use.
Flotation of mineral particles results from the attachment of gas bubbles to the particles while they are suspended in aqueous solutions. The attachment during contact itself is governed by, among other things, the interfacial properties of the minerals and the gas bubbles, as well as, changes in such properties brought about by the addition of various chemicals. The long chain organic electrolytes used in the past as collectors for non-sulfide minerals possess one or more ionic groups and the role of these polar groups in governing non-sulfide flotation is indeed a major one. The ionic head determines whether the collector is anionic or cationic and whether it is completely or partially ionized. In the case of weakly ionizable fatty acids which are widely used for flotation of non-sulfide minerals, it is important to consider their ionomolecular composition and the effect of the composition on the formation of insoluble salts or ionomolecular complexes. [See Hanna, H. S. and Somasundaran, P., "Flotation of Salt-type Minerals," Chap. 8, FLOTATION, Gaudin Memorial Volume 1, Publ. AIME, 1976, pp. 197-272.]
More particularly, fatty acids undergo dissociation as follows: EQU RCOOH.revreaction.RCOO.sup.- +H.sup.+.
The resulting ion forms insoluble salts with multivalent metal ions such as Ca.sup.2+ and Mg.sup.2+. Both the solubility of such collectors and their metallic salts, as well as, their flotation properties are dependent upon chain length, the presence of double bonds in the collector and the co-existence of neutral surfactant molecules and collectors in the solution. These ionic electrolytes have generally been used in combination with extenders generally comprising hydrocarbon oils such as kerosene oil, fuel oil, diesel oil, etc. The use of these hydrocarbon extenders in combination with fatty acid collectors has found commercial application and has provided a considerable improvement in metallurgy as compared with the use of the fatty acid collectors alone.
Although a number of inorganic electrolytes are used in the flotation of non-sulfide minerals either as pH modifiers or as depressants and activators, their roles are not clearly established. These electrolytes are considered to be essential for the formation of hydrophobic multilayers on mineral surfaces but, on the other hand, they are also considered to be harmful due to precipitation as metal salts in the pulp, thereby decreasing the amount of collector available for flotation.
Since the separation of non-sulfide minerals from one another is extremely difficult and sensitive especially when the minerals contain common cations, modifiers are invariably used for obtaining or improving selectivity, as mentioned earlier. In addition to the pH modifying agents, modifiers commonly used include inorganic reagents such as sodium silicate, polyphosphates and aluminum salts as well as organic reagents such as starch, dextrin, tannin, guar gums and the like. pH modifiers are used to produce optimum alkalinity or acidity necessary for the flotation of the desired mineral. While most non-sulfide minerals can be floated using fatty acids in a slightly alkaline medium, the carbonate minerals such as calcite and dolomite respond well to both slightly acidic or alkaline pulps. Flotation of calcite in the pH range of 7-11 is lower than that obtained at other pH values. The interactions of various inorganic and organic modifiers on the flotation of non-sulfide minerals can be attributed to the following four major effects [See Eigeles, M. A., "Selective Flotation of Non-Sulfide Minerals", Prog. Mineral Dressing, Trans. 4th Intl. Minl. Proc. Congr., Stockholm, 1957, Alonquist & Wiksell, 1958, pp. 591-609 and Eigeles, M. A., "Modifiers in the Flotation Process", 1977, "Nedra", Moskow, 216 pp.]:
(1) the effect of the modifier directly on the mineral properties such as surface charge and adsorption capacity for the collector; PA0 (2) reduction in the adsorption of collector on the mineral surface owing to the coating of the surface by the modifier; PA0 (3) the effect on the solution chemistry of the flotation pulp; and PA0 (4) the effects on the frothing characteristics. PA0 (1) direct flotation where fatty acid is used under moderately alkaline conditions to float phosphates, with modifiers used for the depression of gangue minerals; and PA0 (2) reverse flotation where amines are used in nearly neutral pulps to float the silicate or silica minerals. PA0 (a) providing an aqueous slurry of finely divided, liberation-sized ore particles; PA0 (b) adjusting the pH of said slurry to a value of between about 5.0 and about 11.0, depending on the ore selected; PA0 (c) conditioning said slurry with an effective amount of an anionic collector; PA0 (d) thereafter, further conditioning said slurry with an effective amount of a depressant selective for siliceous gangue minerals and materials; said depressant comprising a copolymer or terpolymer derived from: PA0 (e) collecting the non-sufide mineral by froth flotation procedures. PA0 (i) x units of the formula: ##STR5## (ii) y units of the formula: ##STR6## (iii) z units of the formula: ##STR7## wherein R.sup.1 is hydrogen or C.sub.1 -C.sub.4 alkyl; M is hydrogen, an alkali metal cation or an ammonium ion; x represents the residual mol percent fraction; y represents a mol percent fraction of from about 1% to about 50%; z is a mol percent fraction of from about 0% to about 45% and the total molecular weight of the copolymer or terpolymer is between about 500 and about 1,000,000; are selective depressants for silica and siliceous gangue minerals or other acid insolubles in an anionic non-sulfide mineral flotation circuit, under certain conditions. This discovery is completely unexpected because the materials have previously been used to selectively depress value non-sulfide minerals such as fluoroapatite during cationic flotation of silica and acid insolubles in a second stage flotation, i.e., they have heretofore been found not to depress siliceous gangue in cationic circuits, but rather to function as selective depressants for non-sulfide value minerals. Applicants have discovered that the selective depressant action for the copolymer and terpolymers function in a directly opposite manner under anionic flotation conditions. PA0 P.sub.2 O.sub.5 --7.73% (16.85% BPL), PA0 Insolubles 75.60%, PA0 CaO 17.44%. PA0 P.sub.2 O.sub.5 --7.23 (15.8% BPL), PA0 Insolubles--78.00.
One of the most commonly used modifiers in non-sulfide flotation is sodium silicate. Its use is often observed to enhance flotation of calcite, phosphorite, apatite and barite from quartz. Sodium silicate is believed to act in these cases by depressing quartz, as well as, by dispersing the slimes that are often present in the pulps. The problem, however, is that the effect of sodium silicate is often unpredictable and tends to be extremely ore specific. Also, very large dosages are often required. Both the mode of preparation of silicate and the ratio of SiO.sub.2 to Na.sub.2 O are shown to play a role in determining the effectiveness of the silicates as depressants. The ratio of SiO.sub.2 to Na.sub.2 O is believed to be important only above a pH of about 7.0 and at high concentration of silicate. Indirectly, this is probably related to the degree of polymerization of silicates rather than the ratio itself. Contrary to its depressor role at relatively high concentrations, soluble silicate has also been reported to act as an activator at lower levels for the flotation of apatite, cerrusite and malachite. This has been attributed to the interaction of the silicates with polyvalent cations to form insoluble compounds, thereby reducing the interference by these cations on flotation. Some investigators have reported the adsorption of carbonate on phosphate or calcite to be essential for the selective adsorption of water glass at high pH values. The favorable effect of aluminum salts in certain systems, such as those for separation of fluorite from calcite using sodium silicate, has also been reported. In this case, the aluminum salt is considered to aid the fluorite/calcite separation by reducing the depressing action of sodium silicate on fluorite. In addition to its use on metal ions, sodium silicate has also been used in combination with polyacrylamide or starch in the flotation of scheelite, calcite, barite and fluorite ores. [See Hanna, et al, above cited.]
The depressing action of various polyvalent cations and anions on the fatty acid flotation of non-sulfides has been attributed to precipitation of the collector. On the other hand, the presence of polyvalent cations is also known to enhance the flotation of non-sulfides under certain conditions. The commonly used inorganic modifiers in addition to sodium silicate include chromates, dichromates, phosphates, polyphosphates, fluorides and inorganic acids. For example, chromates and dichromates are used individually or in combination with organic colloids for the selective depression of barite. The depressing action of the polyphosphates in the flotation of magnesite from dolomite is believed to be due to the reduction of fatty acid availability and to the dispersion of dolomite slimes from the magnesite surface, as well as, to the selective adsorption of the polyphosphate on dolomite.
Organic modifying agents such as starch, tannin, quebracho, guars and lignins have been used for a number of years for increasing selectivity during non-sulfide flotation. Except for some short-chain organic acids, these reagents are characterized by their high molecular weight, on the order of 10.sup.5, as well as, by the presence of a number of strongly hydrated polar groups such as OH, COOH, --NH.sub.2, SO.sub.3 H and CHO, etc. There are essentially four types of organic modifiers, including (a) anionic compounds, such as starches and tannins; (b) cationic reagents; (c) heteropolar compounds, such as proteins, and (d) non-ionic compounds such as carbohydrates. [See both articles by Eigeles, M. A., above cited].
Anionic compounds such as starches and tannins have been the most popular modifiers for many years. Starches are used in the cationic flotation of quartz from iron and phosphate ores. In this application, starch is believed to depress hematite and phosphate. Starch is also used as a depressant for iron oxides, ilmenite, carbonates, monazite and for the selective flotation of calcite, fluorite and barite from each other using fatty acids as collectors. In these systems, starch depresses calcite, barite and quartz while permitting the fluorite to float. Tannin and quebracho have also been used for the depression of carbonate minerals. Although many of these organic modifiers have been used for many years, the understanding of their depressant action is rather poor. The depressing property of starch is reported to be influenced by the mineral characteristics; the type of starch; the extent of its branching and the number of functional groups on the starch backbone; its mode of preparation; the pH of the pulp and the electrolytes also present in the flotation pulp.
Starch constituents have been reported to form complexes with calcium. Such complex formation could also be partially responsible for the starch adsorption on calcite.
Most reagents depress flotation normally by adsorbing on the mineral particles and thus making their surface unavailable or unsuitable for the adsorption of the collector. In the case of starch and perhaps other natural polymers also, uptake of the collector may even be enhanced on the mineral being depressed in the presence of starch and yet the mineral may remain hydrophilic. This peculiar phenomena has been attributed to the characteristic helical structure of starch which can trap the collector molecules inside the helix, thereby masking the hydrophobic collector. [See Hanna et al, above cited].
In contrast to starch, which possesses a neutral alcoholic OH group with a pKa of greater than 12, tannin compounds are active due to the presence of slightly acidic phenolic OH groups having pKa in the range of 9.2 to 9.9. [See Hanna et al, above cited]. Their depressing action is believed to be due to the formation of complex phenolates or tannates on the mineral surface and also hydrogen bonding and electrostatic interaction between tannin and charged mineral surface. It is also reported that calcium tannate complexes are possible on calcium minerals. As in the case of starch, co-adsorption of tannin with oleic acid has also been observed on the surface of calcite, fluorite and barite. [See Hanna et al, above cited].
As can be seen from the above, conditions for effective froth flotation beneficiation of non-sulfide minerals depend heavily on the particular mineral to be beneficiated, as well as on various interactions of the many modifiers present in the flotation pulp. The solution chemistries involved play a very important role and a priori predictions concerning the nature of any given flotation system are difficult if not impossible to make.
By way of further illustration, this application will concentrate on phosphate ores as illustrative of non-sulfide flotations generally and the problems associated with flotation of these minerals. There are two main types of phosphate ores, namely, igneous and sedimentary types. The igneous ores are macrocrystalline in nature and are found as pegmatites and veins in association with quartz, fluorite, calcite, etc. They are much more easily amenable to flotation beneficiation than the sedimentary types which are microcrystalline. The mineral values are often in a much more finely disseminated form in the sedimentary types. Moreover, there is significant substitution with various chemical species in the sedimentary apatites. These characteristics make it particularly difficult to separate phosphates from sedimentary ores. For ores with low carbonate content, two main flotation techniques are used.
Thus, the beneficiation of southeastern United States phosphates, for example, is achieved by anionic flotation of phosphates followed by cationic flotation of silica from the acid scrubbed and deslimed phosphate concentrates. The anionic flotation is conducted around pH 8-9.5 and the cationic flotation around pH 7-8. In addition to modifiers, various commercial hydrocarbon mixtures such as kerosene and fuel oil are used for increasing the flotation response and thereby reducing the consumption of other flotation reagents. When the ores are of a highly porous sedimentary type, these hydrocarbon oils, referred to as extenders, are commonly required. The presence of polyvalent cations such as Ca.sup.2+ and Mg.sup.2+, Fe.sup.3+, Al.sup.3+, etc. are known to inhibit the fatty acid flotation of phosphates and to activate the siliceous gangue thereby diluting the concentrates obtained in the fatty acid flotation step. Activation of silica during the anionic flotation of phosphates is usually reduced by adding a variety of modifiers, such as fluorides, sodium silicate, or colloidal silica.
In general, for the flotation beneficiation of non-sulfides from siliceous gangue using fatty acids, sodium silicate and sodium carbonate are used commercially to achieve some degree of success. When the gangue is calcarious, organic modifiers with or without sodium silicate are invariably used.
Currently and by way of illustration, a standard method for the beneficiation of phosphate ores is by a double float process whereby the phosphate ore is first floated with any one or more of several well known anionic reagents such as the fatty acids which leave rougher tailings low in phosphate values and a concentrate high in phosphate but also undesirably high in siliceous gangue. This first float or single float product containing considerable quantities of silica, is then scrubbed with sulfuric acid to remove the first flotation reagents, namely the fatty acids and extenders, and then again subjected to flotation using any one of the well known cationic reagents to float the silica, typically amines. The majority of the remaining silica is thereby floated away leaving the double float or second float tailings product high in phosphate values and very low in silica.
This invention relates to an improvement in this two-stage flotation beneficiation process for non-sulfide minerals, including phosphate ores, which contain substantial quantities of associated siliceous gangue minerals. Typically, crude ores are first ground or comminuted and then subjected to various physical methods of concentration to separate valuable minerals from the waste minerals which usually consist of clay, silicas and other minerals having little or no value. Much of the gangue can be removed by water washing, screening and gravity separations, but in most beneficiation processes of siliceous ores, the final and most important step is flotation. Phosphate ore deposits, particularly those in Florida are sub-surface pockets of phosphate ore which can consist mainly of about 1/3 each of sand, clay and calcium fluorapatite. The phosphate contained in the matrix ranges in size from 3/4 inch pebbles down to -150 mesh particles and generally is in the form of discrete grains with rather small amounts of included quartz sand. The free silica is normally mainly -20 mesh. The type and consistency of the clay varies and is mixed but generally is distributed throughout the matrix. The nature of the phosphate pebble and the size of the silica lends the matrix to an effective beneficiation process which consists of the following main steps after mining the ore: (1) washing to remove clay; (2) screening to remove the +16 mesh pebbles generally of a relatively high grade of material; and (3) flotation to recover the -16 to 150 mesh phosphate from silica and clay. Pebble rock removed by screening varies in grade from ore body to ore body but generally ranges from 65 to 75% bpl (bone phosphate of lime or tri-calcium phosphate). Constituting about 10% of the matrix, pebble phosphate is marketable without further processing.
The remaining matrix is chiefly fluorapatite and sand of varying and similar particle sizes which precludes separation by physical means. An elegant and now widely used method of separation of phosphate from sand involves two-stage flotation. In the first flotation stage, flotation reagents such as tall oil fatty acids (the collector) and fuel oil (extender) are used to float phosphate. Anionic flotation of phosphates is non-specific, especially under commercially employed conditions which are designed to produce high BPL recovery required by process economics, and the float concentrate normally contains 10-20% silica impurity. The second flotation stage further reduces the amount of silica and involves scrubbing the concentrate with sulfuric acid to remove the fatty acids (de-oiling) and thereafter floating the silica in the scrubbed concentrate with an amine collector. The final phosphate product contains about 70-75% BPL and less than 5% silica or acid insolubles and a BPL recovery of about 90-95%. Dual flotation as described above is obviously more expensive than the single stage flotation because of additional equipment and reagents needed. It is the method of choice, however, since single stage flotation often cannot provide marketable grade phosphate concomitant with satisfactory BPL recovery. Preventing complete separation with good BPL recovery is the lack of specificity of the anionic collectors for phosphate particles. Searches for more specific collectors or for a selective depressant for silica antedates the development of the two-stage flotation processes referred to above. Such efforts have met with only limited success, as evidenced by the continuing practice of using the two-stage process in phosphate production.
Prior art attempts to improve selectivity and recovery of flotation processes for non-sulfide minerals have included the use of certain synthetic gangue depressants in either the anionic or cationic flotation stages. For example, U.S. Pat. No. 3,862,028, discloses gangue depressants that are graft polymers comprised of a starch substrate onto which is grafted a member selected from the group consisting of a polymerized quaternary ammonium derivative of aminoalkyl methacrylate and mixtures of a polymerized quaternary ammonium derivative of aminoalkyl methacrylate with polyacrylamide. The graft copolymers are prepared by gamma irradiation method. In the preferred embodiment, wheat starch was irradiated with a total dosage of 5 megarads of gamma radiation with a cobalt 60 source. The irradiated starch, under a nitrogen atmosphere, was then brought into contact with a solution of monomer and allowed to react for a time sufficient to obtain maximum grafting. The quaternary ammonium derivative of aminoalkyl methacrylate monomer has the structure: ##STR1## (2-hydroxy-3-methacryloyloxypropyltrimethylammonium chloride)
As disclosed in said patent, the addition levels for flotation reagents, for example, the collectors, activators, extenders or depressants, the orders of addition and the effects of the additives on each other were investigated. The addition level for the graft polymers was from about 0.025 to about 0.2 pounds per ton. The preferred level was from about 0.025 to about 0.05 pounds per ton. The preferred polymer content was from about 2.5 to 15% by weight of the quaternary ammonium monomer in the graft polymer and from about 5 to 20% by weight of acrylamide monomer in the graft copolymer, based on starch, quaternary monomer and acrylamide comonomer. It was found that the graft polymer was best added before the fatty acid collector. The polymer did improve the grade of P.sub.2 O.sub.5 concentrate but only at the expense of P.sub.2 O.sub.5 recovery.
The above-described starch-based depressants, as well as other water-soluble starches, dextrin, guar gums and the like, have several shortcomings. From an ecological vantage point, the presence of residual depressants such as these in the waste waters increases biological oxygen demand and chemical oxygen demand, thereby creating a pollution problem in the disposal of these waste waters. From a commercial vantage point, there are an ever-increasing number of countries in which the use of reagents having food values such as starch, is prohibited in commercial applications. Moreover, the starch type depressants require a complex preparation from the reagent solution involving a cooling stage prior to solution and the resultant reagent is susceptible to bacterial decomposition, thereby requiring storage monitoring. These natural polymers have only limited storage stability.
Another single stage flotation process for separating phosphate minerals is described in U.S. 3,351,257. As disclosed therein, anionic collectors such as fatty acids are employed in combination with certain modifiers for depressing siliceous gangue and dispersing slimes. The modifiers disclosed comprise water-soluble agents including inorganic modifiers selected from ammonium hydroxide, and the ammonium and sodium orthophosphates, metaphosphates, orthosilicates, metasilicates, fluorides and carbonates, and organic modifiers selected from sodium and calcium lignin sulfonates. Best results are obtained with sodium fluoride and the lignin sulfonates and wherein the modifier is added prior to addition of the fatty acid. The modifiers are added at dosages from 0.1 to 2.5 lbs/ton. The process disclosed in the '257 patent improved the selectivity of the flotation separation of phosphate from siliceous impurities. The process also permits the two final separation stages, e.g. acid scrubbing and amine flotation, to be eliminated in recovering phosphate values from phosphate ores. The process is also beneficial in that it provided a reduction in the need for close plant controls in critical areas, such as desliming, sizing, conditioning, and reagent rates, as well as, a reduction in flotation reagent requirements and processing costs. Phosphate recovery was also increased.
In U.S. Pat. No. 4,220,525, it is disclosed that polyhydroxyamines are useful as depressants for gangue materials including silica, silicates, carbonates, sulfates, and phosphates. Illustrative examples of the polyhydroxyamines disclosed include aminobutanetriols, aminopentitols, aminohexitols, aminoheptitols, aminoctitols, pentose-amines, hexose amines, amino-tetrols, etc.
In U.S. Pat. No. 4,360,425, assigned to the same assignee as the present invention, a method is described for improving the results of a non-sulfide froth flotation process wherein a synthetic depressant is added which contains hydroxy and carboxyl functionalities. As disclosed in U.S. Pat. No. 4,360,425, the synthetic depressant is added to the second or amine stage flotation of a double-float process for the purpose of depressing the non-sulfide mineral values i.e., phosphates, during amine flotation of the siliceous gangue materials from the second stage concentrate. This patent relates to the use of the synthetic depressant during amine flotations only, wherein the depressant is added first and then a commercially available amine collector is added later. The results in said patent indicated an improvement in the grade of non-sulfide mineral values maintained in the second stage tailings recovery by the depressant during this second amine flotation of the silica gangue.
Unexpectedly in view of the foregoing, it has now been discovered that very efficient non-sulfide mineral values separation from siliceous gangue may be obtained in an anionic flotation stage using a polymeric depressant by adding the synthetic depressant after the fatty acid collector has been added to the slurry followed by direct froth flotation. In accordance with this discovery, marketable phosphate products have been obtained in a single anionic flotation step thereby eliminating the need for acid scrubbing and subsequent amine flotation. The process of the present invention provides improved grades of non-sulfide value minerals without loss of recovery and no operational modifications are required for conventional equipment. The low molecular weight polymers are very stable and can be stored indefinitely unlike the natural polymers such as starch, dextrin, etc., heretofore employed.
Accordingly, it is an object of the present invention to provide a new and improved process for flotation beneficiation of non-sulfide value minerals from non-sulfide ores which is more efficient by permitting a reduction in the number of flotation steps and in the amounts of flotation reagents required to provide satisfactory grades and recoveries.
It is another object of the present invention to provide a new and improved process for separating non-sulfide value minerals from ores containing associated siliceous gangue minerals and materials, satisfactorily in terms of grade and recovery, and in substantially a single flotation step employing commercially available anionic colletors and plant equipment.